Conventionally, an electric motor with a brush has been widely used as an electric motor mounted on vehicles such as cars. In this type of electric motor, a plurality of magnets are arranged at equal intervals in a circumferential direction on an inner circumferential surface of a cylindrical yoke, and an armature is rotatably supported on an inner side of these magnets. The armature has an armature core having a plurality of radially formed teeth. A plurality of axially long slots are formed between the respective teeth. A winding wire is wound between the slots having a predetermined interval, in, for example, a lap winding scheme.
A type of winding device including a flyer is known as a winding device used to wind a winding wire.
This type of winding device is configured to bring a winding wire from a nozzle provided in a tip of the flyer and wind the winding wire between predetermined slots.
A terminal portion of the winding wire is electrically connected to a commutator externally fitted to the rotating shaft to be adjacent to the armature core. The commutator is disposed in the circumferential direction in a state in which a plurality of segments which are metal pieces are insulated from each other. The terminal portion of the winding wire is connected to each of these segments. Among the plurality of segments, segments having the same electric potential are short-circuited by a connection wire.
Further, a plurality of brushes are slidably connected to each segment. A power is supplied to each winding wire through the brushes. Also, a magnetic field is formed in the powered winding wire, and the armature is driven by magnetically attractive and repulsive forces generated between the winding wire and the magnets of the yoke.
Here, in the winding wire wound between the predetermined slots, tension applied to the winding wire is often different depending on a used winding device, and rotation balance and weight balance of the armature vary due to the wound winding wire. Therefore, it is necessary to adjust the rotation balance or the weight balance of the armature. A method for attaching a modification material to the armature core or a method for cutting out a portion of the armature core is known as a method for adjusting the rotation balance or the weight balance of the armature.
Further, technology used to adjust rotation balance and weight balance of an armature by adjusting the number of turns of a winding wire wound between predetermined slots is disclosed (e.g., see Patent Literature 1).
Further, technology used to adjust rotation balance or weight balance of an armature by adjusting a winding place of a winding wire is disclosed (e.g., see Patent Literature 2).